Extensible ladder rig



Feb. 9,1943. B. KLUM I I 2,310,441

EXTENSIBLE LADDER'RIG Filed May 9, 1939 INVENTOR. .BLA/NE [Qu-M I ATTORNEQNQ- Patented Feb. 9, 1943 UNITED STATES P'E'ENT OFFICE EXTENSIBLE LADDER RIG Blaine Klum, Oakland, Calif.

Application May 9, 1939, Serial No. 272,574

2 Claims.

This invention relates to extensible ladder rigs. Included among the objects of the invention is the provision of an extensible ladder rig having novel means for adjusting the relative position of the movable ladder section with respect to the ground ladder section. Additionally the invention provides means for facilitating the interlocking of the ground and movable ladder sections in a positive manner precluding accidental disengagement of same.

Another object of the invention is the provision of a ladder scaffolding which, while possessing the aforementioned advantages, will meet present day safety requirements.

Other objects of this invention will become more apparent as this specification proceeds and the novelty thereof will be particularly pointed out in the appended claims.

In the drawing forming a part hereof,

Figure 1 is a longitudinal section through an extensible ladder rig embodying my invention, showing the adjustable connection between the ladder elements with the connection in its operative position,

Figure 2 corresponds to Figure 1, showing the adjustable connecting member in its inoperative position,

Figure 3 is a fragmentary front elevation of the subject matter of Figures 1 and 2, and

Figure 4 is a plan view of the slidable connection between the ladder elements with the ladders shown in section.

A surface ladder ll) of conventional construction has a plurality of rungs H, and slidably supports a relatively shorter extension ladder l2. The extension ladder l2 has conventional rungs The slidable connection between ladders Ill and I2 is shown in Figure 4 as consisting of a pair of straps 30. These straps are bolted or otherwise secured to ladder l2 and have their free ends bent to conform to the shape of legs of ladder H], the tips 3| thereof being turned inwardly about the inner edges of the legs of ladder Hi. It will be understood from this that ladder I2 is free to move up and down on ladder l subject only to the action of the elevating and locking means now about to be described.

The locking or latching means comprise two substantially triangular shaped members 35 having an opening therethrough and rigidly attached at their apexes to a rung 36, the ends of which are rotatably received in the sockets 31 bolted or otherwise secured to the legs of the ladder l2 (see Fig. 3). Each of the members 35 is provided with a hook like projection 38 adapted to engage the rungs ll of ladder l5 when in operative position (see Figure 1).

The raising and lowering of the ladder 12 with respect to ladder i0 is accomplished through the provision of a sheave 48, on one of the rungs ll of ladder ii), and a pulley 42, the hook 4! of which engages the upstanding eye 43, medially disposed on rung 36 and forming a short fulcrum therewith. A rope 44, having one end attached to the bottom of sheave 40 (see Fig. 2), is then passed around pulley 42, thence around sheave 40, to render operative the mechanism just described.

A conventional metal tie-rod 45 between the legs of the ladder l2 serves not only to prevent the spreading of the ladder legs but extends through the openings in the locking members and acts as a stop to define the limits of the pivotal movement of said members 35 with rung 36. Particularily is this true in limiting movement of members 35 in counter-clockwise direction (looking at Figures 1 and 2) when weight is transmitted to ladder l2 and by the member 35 to ladder H].

In the illustrated form of the invention the means for swinging locking members 35 into inoperative position (see Fig. 2) consists in passing the free end of the rope 44 over a sheave 46 on tie-rod 45 and connecting the end of rope 44 to a leg of the member 35. The flexible member need not be on end of rope 44; it may be a rope or thong, as desired.

From the foregoing description it will be seen that to disengage the locking means and move ladder 12 with respect to ladder III the operator first pulls downwardly on the looped portion of rope 44 which draws the pulley 42 toward sheave and lifts the hook 38 of lock 35 free of the rung l I. If ladder I2 is to be moved upwardly with respect to ladder l0 and re-engaged the operator need only continue exerting the downward pull on rope 44 since the hook portion 38 of lock member 35 will be moved inwardly by contact with the upper rungs H and, if the pull be continued, will pass each successive rung and return to its rung engaging position. In this movement it will be understood that lock 35 is swung on its pivot against the fulcrum formed by piece 43.

Where, however, ladder I2 is to be lowered with respect to ladder l0, it is obvious that the hook 38 of locking means 35 must be moved and held out of its rung engaging position, and this is accomplished by first pulling downwardly on rope 44 to raise the lock 35 clear of the rung and then drawing the rope 44 outwardly over the sheave 46 to cause the lock member 35 to turn on its pivot and against its short fulcrum 43, into the position indicated in Figure 2, and thus. clear of rungs ll. Rope 44 is then allowed to slip over sheave 40 to lower ladder I2. When the desired adjustment has been made the opposite end of the rope is slackened to allow the hook 38 of element 35 to swing back into its rung engaging position under the urge of pulley 42 on fulcrum 43 on rung 36.

It will be seen from the foregoing that the elevating and locking means disclosed herein provide a valuable safety factor not attainable with the conventional structures in that the accidental dropping or downward movement of the movable ladder section l2 or a working platform supported thereby is obviated because under no condition can the working platform move except by deliberate disengagement of the locking element 35 from the rungs I I.

It is believed that from the foregoing description it will be seen that I have devised an extremely practicable and eflicient extensible ladder rig and one which may be conveniently and quick- 1y adjusted for different heights of work area with but a minimum of effort.

While a preferred form of the invention has been shown and disclosed in this application, it will be appreciated that the principles thereof may take many and varied forms and hence I do not wish to be limited to the form shown only, but rather desire protection in accordance with the full scope of the appending claims.

The invention claimed is:

1. In an extensible ladder rig, a ground ladder, a movable ladder section slidably engaging the ground ladder, a rotatable rung in the movable ladder section, a member projecting from the rotatable rung and disposed intermediate its ends, pulley means anchored on the ground ladder and having an operative connection with the member projecting from the rotatable rung to raise and lower the movable ladder section, a pair of rung engaging lock members rigidly fixed on the rotatable rung and having hooks projecting therefrom substantially at right angles to the member projecting from the rotatable rung, the hooks of said rung engaging lock members being normally but yieldably moved. into the path of the rungs of the ground ladder upon actuation of said pulley means, said rung engaging lock members each having a substantially triangular shaped opening therein, a tie rod connecting the legs of the movable ladder section and extending through the openings in said rung engaging lock members, and flexible means coacting with said tie rods operable at will to move the rung engaging members into inoperative position when the pulley means is being actuated to raise or lower the movable ladder section.

2. In an extensible ladder rig, a ground ladder, a movable ladder section slidably engaging the ground ladder, a rotatable rung in the movable ladder section, a member projecting from the rotatable rung and disposed intermediate its ends, pulley means anchored on the ground ladder and having an operative connection with the member projecting from the rotatable rung, a pair of rung engaging lock members rigidly fixed on the rotatable rung and having hooks projecting therefrom substantially at right angles to the member projecting from the rotatable rung, the hooks of said rung engaging lock members being adapted to be moved into the path of the rungs of the ground ladder upon actuation of said pulley means, said rung engaging lock members each having a substantially triangular shaped opening therein, a tie rod connecting the legs of the movable ladder section and extending through the openings in said rung engaging lock members, and a flexible member connected to said rung engaging lock members and extending over the tie rod for drawing the hooks of the rung engaging members out of the path of the rungs of the ground ladder against the urge caused by actuation of said pulley means.

BLAINE KLUM. 

